1. Field of the Invention
The present invention relates to a double rack and pinion oscillating device, and more specifically, it relates to an oscillating device in which a pair of racks arranged parallel to each other are caused to linearly reciprocate by pistons in opposite directions relative to each other, and an output shaft is thereby caused to rotationally oscillate through a pinion meshed with both the racks.
2. Description of the Related Art
Hitherto, a double rack and pinion oscillating device has been commonly known that includes a pair of pistons having racks arranged parallel to each other, an output shaft having a pinion meshed with both the racks, and supported rotatably around its axis, and in which the pair of pistons are caused to linearly reciprocate in opposite directions relative to each other by fluid pressure, and the output shaft is thereby caused to rotationally oscillate.
In such an oscillating device, when a pair of pistons are caused to linearly reciprocate in opposite directions relative to each other, pressure fluid needs to be alternately supplied to a pressure chamber at one end of one piston and a pressure chamber at the other end of the other piston, and a pressure chamber at the other end of one piston and a pressure chamber at one end of the other piston. However, due to structural and manufacturing limitations, flow paths connecting the pressure chambers can need to be formed so as to straddle the cylinder hole of each piston.
In conventional oscillating devices, as disclosed in the patent documents, Japanese Registered Utility Model No. 2537200 and Japanese Unexamined Patent Application Publication No. 2002-310104, the flow paths are formed by forming flow path grooves in an end plate, or separately preparing a plate in which flow path grooves are formed.
However, in such conventional oscillating devices, it is necessary not only to form complexly-shaped flow path grooves in the surface of a plate but also to prepare complexly-shaped sealing members surrounding the complex flow path grooves, and therefore there is room for improvement in terms of structure and cost.